vlc: add chromecast option

[Stantheman]

Hi, this is adding an option to build VLC with support for chromecasting

[Hoshpak]

Thanks for your first contribution to Void! Please review my comments and amend the commit.

[Stantheman]

Thank you for the very helpful and detailed review @Hoshpak! It was really helpful as a newcomer to xbps. I've pushed up the changes and are waiting for tests to finish up. Please let me know if anything else needs changing. I've tested for a while now locally and followed the guidelines in the contribution document to try to reduce any additional burden

[Hoshpak]

There's just one more thing I forgot to mention earlier. Since the build option is now the default, the resulting binary package will be different than the one currently in the repository. The builders will only rebuild a package if the version or revision of the template is different than the one currently in the repository so please increment the revision number in the template.

[Stantheman]

Awesome, thank you!